Moscow, Feb. 19 -- Over 400 people were detained in Russia while paying tribute to opposition leader Alexei Navalny, who died at a remote Arctic penal colony, a prominent rights group reported. The sudden death of Navalny, 47, was a crushing blow to many Russians, who had pinned their hopes for the future on President Vladimir Putin's fiercest foe. Navalny remained vocal in his unrelenting criticism of the Kremlin even after surviving a nerve agent poisoning and receiving multiple prison terms....